The present invention relates to locking devices and more particularly the invention relates to a locking mechanism for windows, doors or the like.
As commonly found, some window or door locks employ a turnable cam or latch plate adapted to interengage a relatively stationary latch. These "locking" components are usually found adjacent the window glass on the window frame or sill. From a security standpoint such an arrangement leaves room for improvement. Quite obviously unauthorized entry can be effected by breaking the glass, reaching in and rotating the locking cam clear of the latch.
In order to secure the locking cam from unauthorized movement various prior art devices have been employed. For example, it has been suggested to use external padlocks and the like to secure the relatively movable cam plate. Yet, this method has its drawbacks in that keys must be kept or combinations memorized. A better solution is found in U.S. Pat. No. 3,413,830. In this patent a latch assembly is disclosed wherein a locking device is made integral with the latch mechanism. As described, a feature of this invention is the use of rotatable flanges or collars having projecting chordal segments that when placed in predetermined angular positions permits or constrains axial movement of a locking bolt. The position of the locking bolt in turn governs the placing of the apparatus in a locked or unlocked configuration. Axial displacement of the lock bolt governs movement of a lock pin. However, when the lock pin is withdrawn from the apparatus no means is provided for its retention and thus it is prone to being misplaced.